Computer aided contact lens design and fabrication using spline surfaces

a technology of contact lens and computer aided design, applied in the field of computer aided contact lens design and fabrication using spline surfaces, can solve the problems of unnecessarily large representation, inefficient, and inability to address the determination of the optics of the lens by Ducharme, so as to improve the fit, improve the effect of optics, and improve the fi

Inactive Publication Date: 2001-06-05
BARSKY BRIAN A
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Furthermore, Ducharme does not address the determination of the optics for the lens in the case of a spline-based design.
Although he mentions thickness, he does not provide any information that would enable someone to design a lens to achieve desired optics.
This lack of mathematical model results in a representation that is unnecessarily large and inefficient.
Note that even a combination of these prior-art references does not provide the physical features of the present application.

Method used

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  • Computer aided contact lens design and fabrication using spline surfaces
  • Computer aided contact lens design and fabrication using spline surfaces
  • Computer aided contact lens design and fabrication using spline surfaces

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Embodiment Construction

A primary application of spline-based contact lens design is the creation of contact lenses for keratoconus. These lenses need complex posterior surface shapes to accommodate the "cone". As an example, but without limitation, FIG. 21 shows such a keratoconus lens using spline-based mathematical geometry to describe the anterior surface 56, posterior surface 57, and peripheral edge system (PES) 58. The posterior surface has a local region of much higher curvature than the overall surface (minimum radius of curvature of 4.5 mm compared to overall radius of curvature of 7.67 mm) and yet the surface is smooth and the curvature continuously varies across the surface. In FIG. 21a, the surfaces are decomposed into pieces corresponding to FIGS. 2b and 11b, that is, a sequence of annular regions, which are further subdivided by adding a set of radial lines 42, emanating from a given annular border 41 and terminating at the periphery 44, thereby forming a collection of four-sided regions 45, ...

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Abstract

A method of computer-aided contact lens design and fabrication uses spline-based mathematical surfaces without restrictions of rotational symmetry. The spline encompasses any piecewise function with any associated constraints of smoothness or continuity. The method comprises some or all of the following steps: data acquisition, three-dimensional mathematical surface model construction, posterior surface description, ray tracing for anterior surface, and peripheral edge system (PES) design. The result is a mathematical or algorithmic description of a contact lens. Based on the more powerful mathematical representation of splines, these contact lenses can have posterior surfaces that provide a good fit to corneas having complicated shapes. This enables the design and fabrication of lenses (including soft lenses) with good optics for irregularly shaped corneas.

Description

This invention relates generally to the design and fabrication of contact lenses, and in particular to a method using spline-based mathematical surfaces without restrictions of rotational symmetry.Besides the obvious cosmetic aspect, contact lenses generally offer improved visual acuity compared to spectacles. In some cases, the difference is dramatic. For example, in the case of the corneal pathology of keratoconus (a corneal condition in which there is local region of high curvature), contact lenses can often succeed in providing excellent visual acuity (perhaps 20 / 20 using the standard Snellen eye chart) whereas spectacles are not able to provide more than a minor improvement over the uncorrected vision. In addition to improved visual acuity, contact lenses are also indicated for other diverse purposes, such as a medicine delivery system or as a "bandage" for protection of the cornea after erosion, trauma, or surgery.Current contact lenses have shapes formed from relatively simpl...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G02C7/04
CPCG02C7/021G02C7/028G02C7/04
Inventor BARSKY, BRIAN A.
Owner BARSKY BRIAN A
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